Dynamic Nuclear Polarization in the frozen TEMPO/water/glycerol solvent system proceeds through a combination of two mechanisms: Thermal Mixing and the Solid Effect. We are characterizing the dependence of each of these mechanisms on factors such as microwave frequency, microwave power, and the EPR lineshape of the radical in order to increase maximal obtainable signal enhancements. In addition, we are performing electron and nuclear relaxation time measurements in this system in order to quantitative characterize each mechanism. We are also exploring other solvent systems and free radicals which support large DNP signal enhancements.